| In previous study,it was found that the R2R3-MYB transcription factor CsMYB1 transgenic tobaccos show shorter stature,less lateral roots and slower growth.In the CsMYB1 yeast two-hybrid library,a tea plant AUX/IAA family transcription factor was been screen,named CsIAA4.Aux/IAA family is a negative regulatory factors that involve in the auxin signal transduction pathway,In this paper,we analysed the functional of CsIAA4,and the protein-protein interaction between CsIAA4 and CsMYB1.The main results are as follows:1.Tissue specificity showed that CsIAA4 was expressed in leaves,stems and roots,and the expression in root maturation zone,lateral root and root tip was higher.2.CsIAA4 transgenic tobacco showed a series of symptoms of auxin deficiency compared to wild-type tobacco G28,such as shorter stature,smaller leaves and reduced lateral roots.Through the hormone treatment of transgenic tobacco and measuring its root length and number of lateral roots,it was found that the sensitivity of tobacco to auxin is decreased.3.CsIAA4 and CsMYB1 are consistent in tissue specificity,and they are both localized in cell nucleus,and transgenic tobacco phenotype are less lateral roots,shorter primary root,and the interaction between CsIAA4 and CsMYB1 is verified by Pull-Down,BIFC.4.We conducted a bioinformatics analysis of CsIAA4 and found that CsIAA4 has four functional domains.In order to find the interactions sites of CsIAA4 and CsMYB1,we delete the Domain Ⅱ of CsIAA4,which is mediate it ubiquitination to do protein interactions experiments with CsMYB1,the results showed CsIAA4D2 cannot interact with CsMYB1.CsIAA4 inhibit auxin signal transduction and reduce the development of lateral roots and growth of primary root in the tea plant,the inhibition will disappear if CsIAA4 were degraded,but CsMYB1 increases the stability of the CsIAA4 by interacting with CsIAA4.And CsIAA4 accumulate in the plant,accumulation of CsIAA4 inhibit roots response to auxin. |
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